Myopia (Disorder), Refraction Error
Conditions
Keywords
Axial Elongation, Lenslet, Violet Excitation Filter, HALT Technology, Myopia Control
Brief summary
Myopia, or nearsightedness, is increasing rapidly worldwide, especially in children and young adults. This study tested two advanced treatments for slowing myopia progression with one control group: special lenslet spectacles (Stellest with highly aspherical lenslet technology) and violet excitation filter glasses (wavelength 420 nm) and Single vision lenses for controls. The study enrolled 90 participants aged 8 to 20 years from schools and universities in Faisalabad, Pakistan. Participants were randomly assigned to one of three groups: lenslet spectacles, violet filter glasses, or single vision lenses (control group). Visual acuity, contrast sensitivity, Spherical Equivalent and axial length were measured at the start and again after 3, 6, and 9 months and one follow up after cessation of treatment. The study aimed to determine whether these advanced technologies can effectively slow myopia progression compared to standard glasses, providing head-to-head evidence on emerging and established optical interventions for myopia control.
Detailed description
This is a randomized controlled trial (RCT) with three parallel groups. The study was conducted at schools and the Universities in Faisalabad, Pakistan. The total study duration was almost one year (July 2025 to May 2026), with each participant undergoing atleast 3 months of active treatment with 3 follow ups. The sample size was 30 participants per group (total N=90), after drop put of patients, calculated using G\*Power (repeated measures ANOVA, 3 groups × 4 time points, medium effect size f=0.25, α=0.05, power=0.8). Simple random sampling was used, with participants allocated to groups using an online research randomizer. Inclusion criteria: axial myopia (high, moderate, or severe), age 8-20 years, both genders, willingness to wear glasses. Exclusion criteria: other ametropia, contact lens users, prior myopia treatment, ocular or systemic disease, ocular surgery, non-cooperative patients. Lenslet group: Essilor Stellest spectacles with Highly Aspheric Lenslet Target technology, 1.6mm thickness, refractive index 1.56, UV 400nm protection, antireflective coating; worn all waking hours. Violet filter group: plastic lenses with 420nm violet excitation filter; worn 3 hours daily (11 AM to 2 PM) to align with circadian rhythm. Control group: single vision lenses (refractive index 1.56). Primary outcome measures: change in axial length (measured by ocular biometer) and change in cycloplegic refraction. Secondary outcome measures: visual acuity (LogMAR chart), contrast sensitivity (Vistech chart). Follow-up assessments at 3, 6, and 9 months. Statistical analysis: repeated measures Linear mixed model using SPSS version 26 to compare within-group and between-group changes.
Interventions
DEVICELenslet Spectacles
The lenslet spectacles are specially designed spectacle lenses featuring HALT (Highly Aspheric Lenslet Target) technology manufactured by Essilor International (Serial Number: 72426930). The lens design includes a clear distance zone in the center with peripheral areas providing single vision correction. Technical specifications: 5H green covering, multi-dimensional pattern, 1.6mm thickness, refractive index 1.56, UV 400nm protection, antireflective coating. Participants are instructed to wear the spectacles throughout all waking hours. Each participant receives a new pair at baseline. No adjustments are made during the 12-month treatment period unless vision changes require prescription update.
DEVICEViolet Excitation Filter Glasses
The violet excitation filter glasses are prescription glasses incorporating a violet light filter with wavelength 420 nm (range 360-420 nm). Material: CR-39. Filter intensity: 700 nm. Wavelength verified using spectrophotometer (standard error ±0.1 to 1 nm). Participants are instructed to wear the glasses for 3 hours daily, specifically from 11 AM to 2 PM, to optimize impact on circadian rhythm while avoiding disruption of sleep patterns. Each participant receives a new pair at baseline. The filter is integrated into the prescription lenses.
DEVICESingle Vision Lenses
Standard single vision spectacle lenses (SVS index 1.56) with no myopia control features. These are conventional prescription glasses that correct refractive error but do not incorporate lenslet technology or violet filtering. Participants are instructed to wear the glasses throughout all waking hours. Each participant receives a new pair at baseline.
Sponsors
University of Faisalabad
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
SINGLE (Outcomes Assessor)
Eligibility
Sex/Gender
ALL
Age
8 Years to 20 Years
Healthy volunteers
No
Inclusion criteria
* Diagnosis of axial myopia (high, moderate, or severe) * Age between 8 and 20 years (inclusive) * Male or female * Willingness to wear prescribed glasses as instructed * Willingness to attend all follow-up visits (3, 6, and 9 months) * Written informed consent from participant or parent/guardian for minors
Exclusion criteria
* Any ametropia other than axial myopia (e.g., hyperopia, astigmatism \>1.50D) * Current contact lens users * Prior or concurrent myopia treatment other than study interventions * Any ocular disease (e.g., cataract, glaucoma, retinal disorders) * Any systemic disease affecting vision (e.g., diabetes, Marfan syndrome) * History of any ocular surgery * Allergic or physical intolerance to glasses materials * Non-cooperative patients unwilling to comply with study procedures
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Change in Axial Length | Baseline, Month 3, Month 6, Month 9 | Axial length (mm) measured using an A-SCAN biometer (Scanmate 677AB). The measurement represents the distance from the corneal apex to the retinal pigment epithelium. Three measurements are taken for each eye and averaged. This is a continuous anatomical measurement with no theoretical minimum or maximum score. Higher values indicate greater ocular elongation, which is associated with worsening myopia progression. |
| Change in Cycloplegic Refraction | Baseline, Month 3, Month 6, Month 9 | Cycloplegic spherical equivalent refraction (SER), measured in diopters (D) using retinoscopy (Welch Allyn) after cycloplegia. SER is calculated as sphere + (cylinder/2). This is a continuous measurement with no theoretical minimum or maximum value. A decrease in SER (more negative values) reflects progression of myopia, while an increase in SER (less negative or more positive values) reflects reduced myopia or a shift toward hyperopia. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Change in Visual Acuity | Baseline, Month 3, Month 6, Month 9 | Visual acuity measured using the Logarithm of the Minimum Angle of Resolution (LogMAR) Visual Acuity Chart (Precision Vision) at 4 m, 2 m, and 1 m. LogMAR scores typically range from approximately -0.30 (better visual acuity) to 1.60 (poorer visual acuity), although values may extend beyond these limits. Lower scores represent better visual acuity outcomes, and higher scores represent worse visual acuity outcomes. |
| Change in Contrast Sensitivity | Baseline, Month 3, Month 6, Month 9 | Contrast sensitivity measured using the Vistech Contrast Sensitivity Test Chart (Precision Vision) at 1 meter. Contrast sensitivity scores are reported in log contrast sensitivity units and typically range from 0.00 to approximately 2.25. Higher scores represent better contrast sensitivity and visual performance, while lower scores represent poorer contrast sensitivity and visual performance. |
Countries
Pakistan
Outcome results
None listed